I offer webrtc2sip servers for rent, $25/month
as a bonus - will provide you with configured sipml5 web dialer, ready to use with your sip server
Also, can integrate it with asterisk , add online signup and creditcard payments (authtorize.net, paypal ) for additional price,
info: webrtc2sip converts WEBrtc stream (which comes from client's browser) to your SIP server
This WEB dialer works on Android,and all other platforms, which can run latest google-chrome browser.
payment method: paypal